Gilbert707

Alright guys. So I have a 305 91 Camaro RS. I have my single fan hooked up to a switch because it wouldn't run on it's own. I went to smog it today and I failed the carbon high speed test by 3 points. I'm assuming it's because to run the test they needed to have the fan on, and it was running a lot colder than it should have been. He said fixing this may make it pass. He also told me changing the catalytic converter might be a good idea. What's your thoughts on this? Do you think running the engine at the hot temperature it should have been at would make it pass? Is the cat a simple bolt on job and should I go ahead and do that? How can I fix the fan? Is it a relay, a switch...? The fan does work so it's not a fan motor or anything like that. Let me know your thoughts I need to get my baby smogged to renew registration next month.

Ron U.S.M.C.

What temp thermostat are you using ?

The higher the temp. is of the thermostat the hotter the car will run.

You can have fans blowing all they want but if the coolant is not flowing it will not help.

I do not want my car to run higher than 200* and it stays in the 180* range.

I would want to make as few changes to my system as possible in order for it to get hot enough to get into the 200* or higher range to pass smog.

That's why I would try the 195* stock setting thermostat first and see how that acts.

At least the getting the car hot enough might be taken care of.

Gilbert707

I just bought the car a week ago and don't know much of the history. I believe it does not have a thermostat because when you start it up it already has coolant flowing through the radiator. I am going to get a new fan temp switch, coolant temp sensor, and install a new 195* thermostat. In theory, this should cause the fan to be operational on its own, right?

willexoIX

May want to add a fan relay to your list if it still has the original.

Ron U.S.M.C.

Yes the fan will come on and off on its own.

Actually that set up is a very nice one. It will bring the car back to stock.

It will run hot just the way Chevy wanted them to.

The setting for a stock thermal switch in the head is designed to turn on the fan
when coolant temperatures reach 222°F.

I will see if I can find you a few part # concerning different temp. "On" fan switches.

There are a few that start the fan within the temp range you’re looking for but start slightly earlier than the stock setting I believe will work for you.

Here they are. I believe these part # can be cross referenced for other brands. =

A company named BWD ( owned by Standard Motor Co. ) makes fan switches that I have found at Advanced,Kragens and Autozone .

They are a direct after market replacement and are installed in the stock location. Here’s the part #s and fan“on”temperatures.
Part # TFS8 = 204 on
# TFS4 = 211 on
# TFS1 = 224 on
If I was FORSED to use any of those I would defiantly chose the 204 temp. switch.

The 204 switch will put you in the HOT zone without bringing your car to those VERY hot temps.

Here is the TFS8 204* on switch . = http://www.oreillyauto.com/site/c/de...1&keyword=tfs8
You can find all of them here.

Ron U.S.M.C.

I guess threre could be sevrale ways the previous owner wired in that fan.

It could be on its own circuit that he installed with or without a relay.

Or he could have simply taken the wire off of the bad stock switch and put a manual toggle on it.

I was kind of hoping he was smart enough to use the last version.

He can test the stock relay to see if its still being used.

If not he can test for continuity from the fans hot lead to the manual switch to see if its directly wired without a relay.

If its not than there is a relay somewhere in the circuit.

If that's the case he can take the grounded wire from the switch and run it to the new switch in the head.

Side note = So if there's a working relay in the circuit I see no reason to complicate the procedure by wiring in a new one.

If the fans power lead is directly wired to the manual switch, "then" we need a relay.

willexoIX

If that was in response to me Ron, i only meant a replacement relay for the original if it might be bad

Ron U.S.M.C.

Thanks for that. I did not understand.
Sorry if that came off wrong.

I was thinking along these lines.

Sometimes when I try to relay info to an OP if I don't know them I go with the "he might not be familiar with "automotive electrical",
so I keep it as simple as possible.

When they come back showing that there familiar with how circuits, relays, etc. work, I change my approach.

I,m always open to learn something from them,or others that reply.

willexoIX

Lol, its all good Ron.

Gilbert707

Alright guys. So today I went and changed the coolant temp sensor, by the thermi housing. It did not work, the fans still do not turn on automatically. I want to hold off on the new thermi (really don't want to drain my radiator fluid today lol.)

About the manual fan toggle switch. Looks like the previous owner plugged a wire into the fan relay (right on the wire that plugs into the middle of the fan), and another to the battery. It does not look like any wires were cut. Would I have to remove this setup for the fan to work on it's own?

What is my next step from here, replacing the coolant temp switch? (not sure if that's the exact name.) where is it located? On the passenger side of the block between heads 8 & 6?

midias

Who knows what the previous owner hacked. I would probably just wire in a new switch and relay.

Gilbert707

I disconnected the switch. One wire was just stuck into one side of the fan relay, then to the switch. The other was (grounded?) to the battery, then to the switch. I then plugged the fan relay back in and now I'm letting it heat up again to see what happens. I'll update you guys when I know if it worked or not.

Gilbert707

Ok so after taking off the manual switch and plugging the fan relay back in, the fan still does not run on it's own. I let it get to about 230-240 before cutting it off. Scary hot, right?

So I my new question is do I replace the temperature switch, or the radiator cooling fan switch? I'm assuming the latter. I'm actually not even sure there's a difference. I'll link the parts I'm looking at.

http://www.autozone.com/autozone/par...mString=search

http://www.autozone.com/autozone/par...mString=search

willexoIX

Im pretty sure they are the same. And yes I would replace the temp switch. If the switch was run from ground, through the switch, then to the ground trigger on the relay and works, that means your relay is good.

Another thing you can try, remove the single wire from the temp switch and ground it. If the fan comes on then there is your problem. If not, the problem exists elswhere.

Let us know

midias

The circuit should look something like this, with this switch it should come on around 210 and off around 200. I use it and a 180 degree thermostat

92RS shearn

I have a somewhat similar issue but I know its one of two (or both) parts for me. Long ago I busted the SW555 and the PT 770 parts above there when I was installing my headers. In a rush hack job I decided to run it to a switch. Now I am trying to bring it back as intended. I replaced the sensor a few years ago and I replaced the PT 770 harness (same harness as knock sensor I was told) but the fan still would not kick on. When I manually grounded that wire the fan kicks on so I know it is one of those two parts that is not working right. I wonder if i got the wrong type of sensor years ago?

84 1LE

iTrader: (9)

Not the same, top link is fan control (pass head), lower is for the gauge (dr side head) & the sensor you replaced on the stat housing tells the computer eng temp.So the ECM knows when to go from open loop to closed loop (among other things).

Its either the fan switch or the relay.As someone said ground the fan switch to the block (ign on) if the fan doesnt start.Most likely the switch is bad.

Ozz1967

iTrader: (4)

with the manual wire disconnected and everything hooked up factory, does the fan come on with the AC?

If the fan comes on with the AC, bypassing the relay, then it's the relay or the switch and you know the overall circuit is good (inline fuse etc.)

Take the wire off the switch on the head. Ground it, if it works, it's the switch. If it doesn't, replace the relay. Rinse, repeat.

Also, make sure ALL the wires on the relay are seated properly. Mine's a little loose in the harness, found out after two different relays I thought were bad. Noticed the wires were loose and weren't making connection once everything was hooked up.

Gilbert707

Alrite the time has come. Sorry I went dark but financial troubles stopped our project dead in it's tracks.

So today I put in a new thermostat 195*
New fan switch 211*
Changed the fan switch pigtail
Topped off coolant

Now my problem. The fans still won't turn on!

I've read a lot of people say that you need to change the fan relay. But the problem is they also say if the AC turns on my fans that it's fine?! I tried grounding the new pigtail to the battery and turning the key but the fan did not turn on. So, it is the relay right?

Also another thing. Even with the switch and thermostat, the car still starts cycling coolant as soon as you start it up, and the weird thing was my temp gauge wouldn't move for the longest time then instantly shot up all the way to the hot end. It's been about an hour since it's been shut off, fan running, and now the temp is all the way back down. I did not notice a gradual decline I'm assuming it dropped right down like it shot right up.

Gilbert707

Accidental double post

Gilbert707

Okay so I tried a few more things. I'm going to some everything up in this post.

I installed a new thermostat. The new thermostat is a 195*, but it still runs coolant thru the radiator as soon as I start it up. I realized my buddy put the gasket in wrong because it was leaking (will fix tomorrow).

I installed a new coolant temp sensor. It did not make the fans run on their own and I do not believe the old one was broken.

I installed a new fan temp switch and spliced in a new pigtail. It's a 211*. I checked voltage from the pigtail to the fan relay and got 12V. After the new temp switch was installed my temp gauge isn't working! My temp stays all the way down then shoots all the way to the hot end when it's overheating. And the fans still do not run by themselves. After the new fan switch my fan would still run by AC.

I also went ahead and changed the fan relay. After I changed the fan relay the temp gauge was still messed up and now my AC does not turn the fan on!

Seriously confused and really need some guidance. The smog shops in town are telling me I need the fans to run on their own at normal operating temp to have a chance at passing smog. None of them want to be messing with a manual fan toggle switch.

84 1LE

iTrader: (9)

Ground the pigtail to the block, not the batt, if the fan does not run.Then check your wireing/relay/fan & all connectors (relay, fan) & check for voltage as well.

The temp coolant sensor (stat)does nothing for the fan, its for the ecu.The sensor on the driver head controls the gauge.

Chack the stat's installation, but even cold should be some coolant flowing.

Gilbert707

So you're saying there is another sensor on the driver side block for the gauge I need to replace now? I'm using the tfs4 i think and after installing it my gauge got messed up and isn't reading temps.

84 1LE

iTrader: (9)

Said it back on post 17, 2 months ago.tfs= tempature fan switch, key word fan.

Gilbert707

Yes I changed the temp switch on the drivers side of the block. I'll try grounding it like you said tomorrow and redo the thermostat.

I'll get back to everyone tomorrow.

Ozz1967

iTrader: (4)

The "Fan" temp switch is in the passenger side of the block, just forward of the dipstick. Controls when the fan comes on. The temperature gauge sensor is in the drivers side of the block and only sends the reading to the gauge in the car.

Gilbert707

I have a 91 Camaro RS 5.0 TBI. You're telling me I just replaced my temp gauge sensor with a temp switch?! How come everyone says it's on the drivers side of the block?!

willexoIX

Ok. Fan switch to turn the fan on is on the passenger head. Coolant temp sensor for the ECM only is by the thermostat. Coolant temp sensor for the gauge only is on the drivers side head. All of this has been stated before.

Gilbert707

Yeah I f'd up pretty bad people. Can the temp switch be done open hood like the gauge temp sensor? Just gonna put the old gauge temp sensor and pigtail back on then put the new temp switch in the right place.

Gilbert707

Okay everyone. So, the temp sensor for the gauge is back to normal and working again. I put the new temp switch in the right place this time and replaced the pigtail because the old one looked janky. After all that the fans still do not run. I'm letting the car cool back down now. I still can't run the fans with the AC anymore. My AC never worked but it use to turn the fans on, not anymore though. Any more suggestions now that we're on the same page?

Gilbert707

Okay so now that I have the switch and pigtail set up properly I'm going to try this next. How would I properly ground the pigtail to the block? And where should I be checking for voltage? Any other ideas of what I should be looking for are appreciated. I have my dads friend helping me out later and he knows a lot more about electrics so don't be afraid to get technical, he'll probably know what you're talking about.

Ozz1967

iTrader: (4)

1. does the fan still come on with power? (run power strait to it from the battery to check).
2. Take the wire off the switch on the passenger side head. Ground it to chassis ground. Run the car up to temp. does the fan come on?

3. On the fan relay up by the brake booster, short the fat power wire on the connector directly to the other connector that goes to the fan bypassing the realy. .does the fan come on?

If you aren't getting any power, even after shorting past the relay with the wire grounded, then you possibly shorted out the fuseable link that's in front of the relay.

This is my first guess since you don't have power with the AC on anymore. If you had power to the fans with the AC onn, then I'd say either the fan switch or the relay was bad.

Gilbert707

Step 1 worked. Fans came on.

Step 2 I grounded the pigtail to the starter and it worked. Fans came on.

(I also tightened the switch more)

Step 3 I tried putting a paper clip from the green wire pin to the red wire pin and it did not turn the fans on but the paper clip got really hot and burnt the hell out of me. Don't think I did this step right.

Btw the AC miraculously turns the fan on again. I'm guna try letting it heat up again and see what happens. Any other suggestions welcome at this point I'll get back to you guys after letting it heat back up.

willexoIX

Sounds like you shorted power to ground on step 3. You want to jumper the 2 fat wires in the relay, I believe one is red or orange, and the other should be the black with red stripe. They are the 2 biggest wires in the relay, and also have the 2 biggest connectors in the relay connector.

Gilbert707

Thread closed guys! Thanks for all the help my fan is now running on it's own! My gauge reads just over 220 when my fan kicks in. It cuts out at about 200 or so. The TFS4 says it's a 211 temp, my gauge could just be off though. No big deal. Thanks again everyone.

Maybe you guys could point me in the right direction about another issue.

When I'm at a stop and a floor it there's a thud from under the car. It sounds like it's directly under the gear box and it's only when I floor it from a stop. Transmission mounts maybe?

Also when I first start my car it idles high. Like 2.4K RPM. As it warms it lowers down to like 1.5 and stays there awhile. After that it drops to like 1.2K and at that point when I shift into reverse my car dies. It starts back up and if I'm quick it can get into reverse no problem. But if I'm warmed up my car dies a lot on a 3 point turn because it starts to idle too low. IAC maybe?

Ozz1967

iTrader: (4)

Always happy to help! Glad its running well!